The efficiency of conversion of ingested food to unit of body substance (ECI, also termed "growth efficiency") is an index measure of food fuel efficiency in animals. The ECI is a rough scale of how much of the food

ingested Ingestion is the consumption of a substance by an organism. In animals, it normally is accomplished by taking in a substance through the mouth into the gastrointestinal tract, such as through eating or drinking. In single-celled organisms inges ...

is converted into growth in the animal's mass. It can be used to compare the growth efficiency as measured by the weight gain of different animals from consuming a given quantity of food relative to its size. The ECI effectively represents efficiencies of both digestion (approximate digestibility or AD) and metabolic efficiency, or how well digested food is converted to mass (efficiency of conversion of digested food or ECD). The formula for the efficiency of food fuel is thus: :

ECI=AD \times ECD\!

These concepts are also very closely related to the

feed conversion ratio In animal husbandry, feed conversion ratio (FCR) or feed conversion rate is a ratio or rate measuring of the efficiency with which the bodies of livestock convert animal feed into the desired output. For dairy cows, for example, the output is mi ...

(FCR) and feed efficiency.

References

Food science Metabolism {{med-stub